Leadless chip carrier sockets are known for removably socketing leadless chip carriers or packages which have no protruding electrical leads but which have contact sites or pads to which electrical contact must be made. However, such known leadless chip carrier sockets are not satisfactory in terms of contact reliability, especially where sophisticated packaging results in increasing pin densities and consequently in greater numbers of contacts.
Former technology used plated through-holes or surface mounted IC chips soldered directly to the board. With today's density of chip carriers, these techniques are not easy to achieve. If an IC chip becomes defective, replacing a soldered chip becomes more difficult than using a socket. Plastic IC chip carriers with high pin count have relatively small leads that are more difficult to solder to a printed circuit board. Extra cost is added to protect IC chip carriers during handling and transportation.
Today's high numbers of closely spaced contacts make it important to protect the leads of the IC chip carrier to maintain their proper position. Damage or misalignment of the chip carrier leads can cause an unreliable electrical connection. With higher speeds of systems, the chip carriers require shorter lead lengths to reduce capacitance and inductance. Current package styles may have no leads. Thus, difficulties arise in socketing leadless components in printed circuit boards and in test fixtures.
As it is very difficult to remove high density leadless chip carriers that have been installed on a printed circuit board, it is desirable to socket such devices, prior to installation, to exercise internal circuitry. A suitable socket is needed for functional and accelerated life testing.